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In Japan, a Long-Term Study on Radiation Leaks’ Effects

TOKYO — In an effort to track the long-term health effects of the nuclear disaster at Fukushima, Japan has begun a survey of local children for thyroid abnormalities, a problem associated with exposure to radiation.

The study comes in response to concerns over the health consequences of the serious radiation leaks caused by multiple meltdowns at the Fukushima Daiichi Nuclear Power Station in March. Japanese officials hope to study about 360,000 children who were under 18 at the time of the accident and track their health through their lifetimes, according to Fukushima Prefecture officials.

Children and pregnant women are particularly sensitive to radioactive iodine, which can harm the thyroid, studies after the Chernobyl nuclear disaster in 1986 have shown. According to research presented at a 2006 global conference, at least 4,000 cases of thyroid cancer among children have been linked to Chernobyl’s fallout.

On Sunday, the first day of the Fukushima study, more than 100 children were tested. Specific test results will not be made public, according to Fukushima Prefecture. But the children, who will be tested every two years until they turn 20 and every five years after that, will receive further care if doctors discover abnormalities.

Almost 20,000 people were killed in the earthquake and tsunami that struck eastern Japan on March 11 and also ravaged the Fukushima plant, leading to a huge release of radioactive substances into the environment. Although no deaths have been linked to radiation, concerns remain high over its long-term health effects.

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Tens of thousands of people are unable or unwilling to return to their homes because of fears of contamination in the area. An evacuation zone remains in effect in a 12-mile radius from the Fukushima plant, though some areas have been exempted in a bid by the government to reassure evacuees that it is safe to return.

Officials in those regions have begun decontaminating public areas by removing the topsoil from school playgrounds and hosing down roads and buildings. Government officials have acknowledged, however, that areas closer to the stricken plant may be off limits for decades.

A team of experts from the International Atomic Energy Agency arrived in Fukushima on Sunday to monitor Japan’s decontamination efforts. The team will visit schools and farms and meet with government officials throughout Fukushima, the agency said on its Web site. It is the nuclear agency’s second major mission to Japan since the accident.

A version of this article appears in print on October 11, 2011, on Page A6 of the New York edition with the headline: In Japan, a Long-Term Study On Radiation Leaks’ Effects. Order Reprints|Today's Paper|Subscribe